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Discussion Starter · #1 ·
I'm leaving work this afternoon and get the 2 alerts Service StabiliTrak and Service Brake Assist. No driving issues during the 10 mile trip of mostly highway driving. I get home and use my ELM with Car Scanner iPhone app to pull codes. The two codes are U0415 and C0035. The Car Scanner app is confused (perhaps) on interpreting the codes. Here's the text from the app:
EPS / TDM
U0415
Status: DC supported by calibration, Current DTC,
History DTC
Possible decryptions (note control module):
OBDI1: Invalid data received - anti-lock brake system
(ABS) control module
Chevrolet: Invalid Data Received From Electronic Brake
Control Module Message Counter Incorrect; Invalid
Data Received From Electronic Brake Control Module
Bus Signal Checksum Error
General Electrical Failures [0x00]
Click to search for description on the Internet.
ABS/EBCM/ESC
C0035
Status: DC supported by calibration, Current DTC,
Test not passed since DTC cleared, Test failed since
DC cleared, History DTC, Test not passed since
current power up, Warning Indicator Requested
Possible decryptions (note control module):
OBDI1: Right Front Wheel Speed Sensor Supply
Chevrolet: Left wheel speed sensor circuit malfunction;
Left Front Wheel Speed Sensor Circuit Low Voltage/
Open; Left Front Wheel Speed Sensor Circuit Signal
Erratic: Left Front Wheel Speed Sensor Circuit Low
 

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Sounds like you're not trusting your meter software, which is a bad place to be in. I don't think this is your issue, but to put your heart to rest, have you tried removing the software and reinstalling fresh.

I think you vehicle is doing it's job, i.e., it is receiving invalid data from your sensors and it is alerting you to this fact. Have you checked your wheel sensors AND the wire harness/bus/connectors of same? If it were me, I would start there. I had a similar problem, coincidently shortly after I had my rotors replaced and some brake work done. In hindsight, I suspect the mechanic may have been a bit heavy handed during the repair, left the caliper hanging by the wire harness during repair or whatever. I replaced the sensor and the wire harness and problem gone. GM has a replacement wire harness or bus I think they called it. The part number I believe was 10340314 . After the repair I took the old harness apart and found one of the wires leading the the sensor was kind of kinked and I noticed that the insulation around that wire was very spongy and easily stretched when manipulated. I stripped the wire back and sure enough, the wire was frayed inside the wire insulation and hanging on by one thread.

Obviously, this may not be your problem so mileage may vary. Also,, if you're really losing confidence in your meter, have the car scanned by another meter, even if you have to pay, just to confirm/deny that your meter is the issue (I really don't think it is in this case, but who knows - wouldn't be the first time software was corrupt).

Good luck!
 

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Because you have multiple Left front sensor codes, I would suspect that is your issue. No way to check sensor other than to replace it with a Genuine GM one. Aftermarket ones are not reliable.
Sensor failure C codes can trigger the U codes as the bad sensor is corrupting the communication system.
Trust what the scan tool says the system is reporting as the system is self-diagnosing itself.
 

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Discussion Starter · #4 ·
I replaced the Left front sensor with a new AcDelco sensor. Cleared both the U0415 and C0035 codes. Test drove and immediately got the codes back.

And btw, my engine is a 2.5. Sorry, I missed the req't to include this....
 

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Discussion Starter · #5 ·
Sounds like you're not trusting your meter software, which is a bad place to be in. I don't think this is your issue, but to put your heart to rest, have you tried removing the software and reinstalling fresh.

I think you vehicle is doing it's job, i.e., it is receiving invalid data from your sensors and it is alerting you to this fact. Have you checked your wheel sensors AND the wire harness/bus/connectors of same? If it were me, I would start there. I had a similar problem, coincidently shortly after I had my rotors replaced and some brake work done. In hindsight, I suspect the mechanic may have been a bit heavy handed during the repair, left the caliper hanging by the wire harness during repair or whatever. I replaced the sensor and the wire harness and problem gone. GM has a replacement wire harness or bus I think they called it. The part number I believe was 10340314 . After the repair I took the old harness apart and found one of the wires leading the the sensor was kind of kinked and I noticed that the insulation around that wire was very spongy and easily stretched when manipulated. I stripped the wire back and sure enough, the wire was frayed inside the wire insulation and hanging on by one thread.

Obviously, this may not be your problem so mileage may vary. Also,, if you're really losing confidence in your meter, have the car scanned by another meter, even if you have to pay, just to confirm/deny that your meter is the issue (I really don't think it is in this case, but who knows - wouldn't be the first time software was corrupt).

Good luck!
The one thing that confused me was in the C0035 text: OBDII indicating Right front but Chevrolet indicating Left front. As my car is a Chevrolet, I "trusted" the Chevrolet one. I'm replacing the Left front which includes approx 2 feet of harness and connector; terminated at anchor point on frame rail.
 

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Right sensor could be corrupting the system. I would change it before thinking the brake control module was bad. Sensors cheaper than the module.
Check the brake module connectors for corrosion. An electronics cleaner / lubricant spray is best used in the connectors.
The codes help point the direction of diagnosis, but weird stuff still can happen.
As a side note, Rock Auto is out of stock on ABS modules so that makes me think it may be a possibility as the U0415 can be a bad module.
|What are the Possible Causes of the Code U0415 Chevrolet?
  • Faulty Electronic Brake Control Module
  • Electronic Brake Control Module harness is open or shorted
  • Electronic Brake Control Module circuit poor electrical connection
 

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Agree with @repairman54 that weird stuff can happen. Particularly with the bad "checksum" error. You're not getting an "implausible" or "out of range" error. Bad checksum would indicate that the OBD packet does not contain expected data or is otherwise corrupt or just one segment of the packet is corrupt or unreadable. And their are various segments of an OBD packet, i.e., source, destination, priority, actual data, etc. It is the equivalent of you sending mail to a friend and the City and State, for example, are illegible. When that envelope (or in this case the ODB packet) are received by the post office and the expected information is not on the envelope or unreadable, the post office is going to lose it's mind and not know what to do with your envelope. So I think @repairman54 is giving you good advice about the potential "weirdness" and also starting with the cheap stuff first. It would really suck to go through the trouble of replacing the ABS module to only find out later that it was the right side sensor had a case of the hiccups.

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